1. Field of the Invention
The invention relates generally to storm water capturing systems, and more particularly to a device for removing hydrocarbons from storm water as it exits the catch basin of a storm water capturing system.
2. Description of the Related Art
Precipitation that falls on a surface that cannot absorb it must be directed to a reservoir or a waterway that carries the water away from the surface. This occurs commonly in paved parking lots and streets. Ordinarily the water is directed by gravity into catch basins, which are steel, cast iron, or pre-cast concrete receptacles buried in the ground. The catch basins' openings are at the surface level and are covered by perforated metal covers, through which water can flow into the catch basins, and over which vehicles can drive. Underground pipes connect the catch basins together to direct storm water into a nearby river, stream, or reservoir.
Unfortunately, much of the storm water that washes into storm water systems carries foreign matter with it. This foreign matter can include naturally occurring materials such as soil, sand, branches and leaves. However, it often also includes refined chemicals such as automobile antifreeze, motor oil, fuel and other hydrocarbons that leak from automobiles. Additionally, the very pavement that makes up many road and parking lot surfaces includes hydrocarbons (in the form of asphalt) that leach into storm water.
Hydrocarbons, which float on water, become an environmental concern because they end up in water that is a potential source of drinking water and/or contains wildlife. It is therefore desirable to remove hydrocarbons that are carried by storm water.
Many people have attempted to address this environmental concern by constructing devices for removing hydrocarbons from storm water. U.S. Pat. No. 5,364,535 discloses a fabric that is mounted in a storm sewer catch basin beneath the perforated cover. The fabric absorbs oily pollutants but does not absorb water. However, hydrocarbons in the water coming in through the perforated cover will not be thoroughly removed because the water falls onto the top of the fabric material and prevents it from absorbing the hydrocarbons that float on top of the water.
It is also known conventionally to use filters at the opening of a catch basin. However, such filters often become blocked as larger objects, such as sticks and leaves, are filtered out and eventually obstruct the passage of water through the filter. Such obstruction can cause the storm sewer system to overflow, thereby defeating the purposes of both the storm sewer system and the hydrocarbon removal device.
Therefore, the need exists for a hydrocarbon removal apparatus that is reliable and does not block water flow. This apparatus should be easily accessed from the surface of the parking lot or roadway, and should remove substantially all of the hydrocarbons from storm water.